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Abstract:

A circuit configuration for providing a voltage supply for a driver
circuit driven by a controller, contains a controller for driving a
driver circuit, and an intermediate circuit for providing a DC voltage.
The intermediate circuit is connectable to a voltage source. A first
voltage regulating circuit is provided for generating an auxiliary
voltage from the DC voltage. A second voltage regulating circuit is
provided for generating a first supply voltage for the controller from
the auxiliary voltage. A third voltage regulating circuit is provided for
generating a second supply voltage for the driver circuit from the
auxiliary voltage. In this case, the third voltage regulating circuit
generates the second supply voltage in a manner dependent on a control
signal from the controller.

Claims:

1. A circuit configuration for providing a voltage supply for a driver
circuit, the circuit configuration comprising: a controller for driving
the driver circuit and outputting a control signal; a first voltage
regulating circuit for generating an auxiliary voltage from an available
DC voltage; a second voltage regulating circuit for generating a first
supply voltage for said controller from the auxiliary voltage; and a
third voltage regulating circuit for generating a second supply voltage
for the driver circuit from the auxiliary voltage or the first supply
voltage for said controller, said third voltage regulating circuit
generating the second supply voltage in a manner dependent on the control
signal from said controller.

2. The circuit configuration according to claim 1, wherein said second
voltage regulating circuit has a series regulator.

3. The circuit configuration according to claim 1, wherein: the second
supply voltage is greater than or equal to the auxiliary voltage; and
said third voltage regulating circuit has at least one of a boost
controller or a charge pump.

4. The circuit configuration according to claim 1, wherein: the second
supply voltage is less than or equal to the auxiliary voltage; and said
third voltage regulating circuit has a buck controller.

5. The circuit configuration according to claim 1, wherein said
controller is configured such that it generates the control signal for
said third voltage regulating circuit in a manner dependent on a
fault-free functionality of at least one of the driver circuit or a
circuit driven by the driver circuit.

6. The circuit configuration according to claim 1, wherein a magnitude of
the second supply voltage for the driver circuit is controllable by said
controller.

7. The circuit configuration according to claim 1, further comprising an
intermediate circuit for providing the available DC voltage, said
intermediate circuit being connectable to a voltage source.

8. The circuit configuration according to claim 7, wherein said
intermediate circuit contains a rectifier circuit.

9. The circuit configuration according to claim 1, further comprising an
additional circuit, a magnitude of the second supply voltage for the
driver circuit is controllable by said additional circuit.

10. A method for providing a voltage supply for a driver circuit driven
by a controller, which comprises the steps of: generating an auxiliary
voltage from an available DC voltage; generating a first supply voltage
for the controller from the auxiliary voltage; and generating a second
supply voltage for the driver circuit from the auxiliary voltage or the
first supply voltage in a manner dependent on a control signal from the
controller.

11. The method according to claim 10, which further comprises providing a
circuit configuration having the controller for driving the driver
circuit and outputting the control signal, the circuit configuration
further containing: a first voltage regulating circuit for generating the
auxiliary voltage from the available DC voltage; a second voltage
regulating circuit for generating the first supply voltage for said
controller from the auxiliary voltage; and a third voltage regulating
circuit for generating the second supply voltage for the driver circuit
from the auxiliary voltage or the first supply voltage for the
controller, the third voltage regulating circuit generating the second
supply voltage in a manner dependent on the control signal from said
controller.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the priority, under 35 U.S.C. §119, of
German application Nos. DE 10 2009 053 909, filed Nov. 20, 2009, and DE
10 2010 022 001, filed May 29, 2010; the prior applications are herewith
incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

[0002] The present invention relates to a circuit configuration for
providing a voltage supply for a driver circuit driven by a controller,
and to a method for providing a voltage supply for a driver circuit
driven by a controller.

[0003] Semiconductor switches, in particular power transistors for
switching high currents and voltages, such as are used in a power
semiconductor bridge for driving a motor, for example, often requires
specific driver circuits for generating the control signals which control
the switching-on and switching-off of the power transistors. In this
case, the driver circuits are usually driven by a controller such as a
microcontroller, for example.

[0004] Generally, a circuit configuration or electronic unit used for
driving a motor requires a plurality of different supply voltages, which
are predetermined by the components to be supplied. The requirements made
of these supply voltages with regard to accuracy, ripple, loading
capacity, etc. are as different as the required voltage levels. Thus, by
way of example, a microcontroller typically requires a very accurate and
loadable 3.3 V supply voltage, while peripheral components such as
operational amplifiers, relays, drivers and the like require a 5-15 V
supply voltage with an average accuracy requirement.

[0005] The energy for generating these supply voltages is often drawn from
an intermediate circuit. Since each voltage level means circuit outlay
and hence space requirement and costs, it is conventionally the case that
usually only two different voltages are generated and continuously
provided. They are typically 3.3 V for the microcontroller and 15 V for
the remaining loads.

[0006] However, this concept has the now described disadvantages.

[0007] First, if the electronic unit is in the quiescent state, most of
the loads which are connected with motor operation are not required, but
nevertheless continue to load the supply voltage, which has to be
continuously provided on account of other loads.

[0008] Second, some loads, such as some operational amplifiers, for
example, have a variable voltage input of typically 5 to greater than 15
V and require a constant current independently of voltage. Therefore, it
is disadvantageous with regard to the power loss to supply them with 15
V.

[0009] Third, the microcontroller configures its ports during power-up.
Its outputs that drive the driver stage are possibly not defined in this
time. If the supply voltage for the driver circuit is already present at
this point in time, this can lead to undesirable switching-on of the
power semiconductors.

[0010] Fourth, the larger auxiliary voltage of 15 V, for example,
generated from the intermediate circuit supplies the peripheral
components and serves as a source for the lower auxiliary voltage of, for
example, 3.3 V for the controller. This lower supply voltage for the
controller is generated from the larger auxiliary voltage by a series
regulator, for example, which is highly lossy on account of the
relatively large voltage difference.

[0011] Published, non-prosecuted German patent application DE 101 33 204
A1 describes a method for generating the supply voltage for driver
circuits by coupling-out from the power section.

[0012] Published, non-prosecuted German patent application DE 10 2007 061
978 A1, corresponding to U.S. patent publication No. 20090160534,
discloses a circuit configuration for providing a voltage supply for a
plurality of driver circuits. This conventional circuit configuration
contains a first bootstrap circuit having a first capacitor, to which a
first auxiliary voltage is fed, and also a first charge pump for
providing the voltage supply for the first driver circuit, a second
bootstrap circuit having a second capacitor, to which a second auxiliary
voltage is fed, for generating the input voltage for the first charge
pump of the first bootstrap circuit, and a second charge pump for
generating the second auxiliary voltage. While the input voltage of the
first driver circuit is provided by the first bootstrap circuit, the
second driver circuit is supplied directly by the first auxiliary
voltage.

SUMMARY OF THE INVENTION

[0013] It is accordingly an object of the invention to provide a circuit
configuration and a method for providing a voltage supply for a driver
circuit which overcome the above-mentioned disadvantages of the prior art
methods and devices of this general type.

[0014] The circuit configuration according to the invention provides a
voltage supply for a driver circuit driven by a controller. The circuit
configuration contains a controller for driving the driver circuit, a
first voltage regulating circuit for generating an auxiliary voltage from
an available DC voltage, a second voltage regulating circuit for
generating a first supply voltage for the controller from the auxiliary
voltage, and a third voltage regulating circuit for generating a second
supply voltage for the driver circuit from the auxiliary voltage. The
third voltage regulating circuit generates the second supply voltage in a
manner dependent on a control signal from the controller. Alternatively,
the third voltage regulating circuit is suitable for generating a second
supply voltage for the driver circuit from the first supply voltage for
the controller, wherein the third voltage regulating circuit generates
the second supply voltage in a manner dependent on a control signal from
the controller.

[0015] In the case of this circuit configuration, first an auxiliary
voltage is generated from an available DC voltage by a first voltage
regulating circuit. The potential of the auxiliary voltage can be
configured, with regard to the power loss, optimally, for the peripheral
components, which usually have a constant current consumption.

[0016] The generation of the first supply voltage for the controller (e.g.
microcontroller) by the second voltage regulating circuit from the
auxiliary voltage can be carried out with relatively low losses since the
voltage difference between the auxiliary voltage and the first supply
voltage can be chosen to be relatively small.

[0017] The second supply voltage for the driver circuit is likewise
generated from the auxiliary voltage by the third voltage regulating
circuit. Since the third voltage regulating circuit generates the second
supply voltage for the driver circuit in a manner dependent on a control
signal from the controller, the second supply voltage is generated, in
particular, only when it is actually required by the driver circuit.

[0018] In this way, it is possible to reduce the power loss of the circuit
configuration in standby in comparison with conventional circuit
configurations wherein the supply voltage for the driver circuit is
continuously generated. Moreover, it is possible to avoid incorrect
driving of the components driven by the driver circuit for example in
standby or during the initialization of the controller.

[0019] The second voltage regulating circuit has a series regulator, for
example.

[0020] In one configuration of the invention, the second supply voltage is
chosen to be greater than or equal to the auxiliary voltage. In this
case, the third voltage regulating circuit has, for example, a boost
controller and/or a charge pump.

[0021] In an alternative configuration of the invention, the second supply
voltage is chosen to be less than or equal to the auxiliary voltage. In
this case, the third voltage regulating circuit has a buck controller,
for example.

[0022] In yet another configuration of the invention, the controller is
configured in such a way that it generates the control signal for the
third voltage regulating circuit in a manner dependent on a fault-free
functionality of the driver circuit and/or a circuit driven by the driver
circuit. In this way, it is possible to realize a so-called watchdog
function with the circuit configuration according to the invention in a
simple manner and, in particular, without additional circuits or
components.

[0023] Furthermore, the magnitude of the second supply voltage for the
driver circuit can optionally be controllable by the controller itself or
by an additional circuit.

[0024] In a further configuration of the invention, the circuit
configuration furthermore has an intermediate circuit for providing the
DC voltage, the intermediate circuit being connectable to a voltage
source.

[0025] The intermediate circuit can contain a rectifier circuit, for
example.

[0026] In the method according to the invention for providing a voltage
supply for a driver circuit driven by a controller, an auxiliary voltage
is generated from an available DC voltage; a first supply voltage for the
controller is generated from the auxiliary voltage; and a second supply
voltage for the driver circuit is generated from the auxiliary voltage in
a manner dependent on a control signal from the controller.
Alternatively, the second supply voltage is fed from the first supply
voltage.

[0027] Preferably, the above-described circuit configuration of the
invention is used for carrying out this method for providing the voltage
supply for the driver circuit.

[0028] The above-described circuit configuration and the above-described
method according to the present invention can advantageously be used for
driving motor drives. In particular they are also suitable for motor
drives in electronic domestic appliances such as, for example, washing
machines, tumble dryers, dishwashers and the like.

[0029] The electronic circuit components "intermediate circuit", "series
regulator", "boost controller", "buck controller", "charge pump" and the
like are sufficiently known to the person skilled in the art with regard
to construction and functioning. In this regard, the present invention is
intended not to be restricted to specific embodiments of these
components.

[0030] Other features which are considered as characteristic for the
invention are set forth in the appended claims.

[0031] Although the invention is illustrated and described herein as
embodied in a circuit configuration and a method for providing a voltage
supply for a driver circuit, it is nevertheless not intended to be
limited to the details shown, since various modifications and structural
changes may be made therein without departing from the spirit of the
invention and within the scope and range of equivalents of the claims.

[0032] The construction and method of operation of the invention, however,
together with additional objects and advantages thereof will be best
understood from the following description of specific embodiments when
read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0033]FIG. 1 is a schematic illustration of a circuit configuration in
accordance with a first exemplary embodiment according to the invention;

[0034] FIG. 2 is a schematic illustration of the circuit configuration in
accordance with a second exemplary embodiment according to the invention;
and

[0035] FIG. 3 is a schematic illustration of a driving of a driver circuit
for the circuit configurations in FIGS. 1 and 2.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Referring now to the figures of the drawing in detail and first,
particularly, to FIGS. 1 and 3 thereof, there is shown a first exemplary
embodiment of a circuit configuration for providing a supply voltage for
a driver circuit will now be explained in greater detail.

[0037] As illustrated in FIG. 3, a controller CTR, for example a
microcontroller, drives a driver circuit DR. The driver circuit DR, in
turn, switches the power semiconductor switches of a power semiconductor
bridge LHB of a motor (e.g. drive motor of a laundry drum of a washing
machine or of a tumble dryer).

[0038] While the motor windings are supplied, via the power semiconductor
bridge LHB, with a DC voltage V+ made available by an intermediate
circuit, for example, as explained later, the driver circuit DR requires
a supply voltage V2 of approximately 15 V, for example. As explained
below with reference to FIG. 1, the supply voltage V2 is generated only
as necessary by a voltage regulating circuit HS or LP, which is driven by
the controller CTR.

[0039] Referring now to FIG. 1, the intermediate circuit voltage V+, which
is generated by an intermediate circuit ZK, serves as voltage source for
all of the loads. The intermediate circuit ZK is connectable to a mains
system LN and has a rectifier circuit and an intermediate circuit
capacitor in order to generate the intermediate circuit voltage V+ by
rectifying the mains system voltage.

[0040] An auxiliary voltage V1 having the magnitude of 5.5 V, for example,
is then generated from the intermediate circuit voltage V+ by a first
voltage regulating circuit in the form of a conventional buck controller
TS. The auxiliary voltage V1 directly supplies the various peripheral
components (e.g. operational amplifiers, comparators, communication,
drivers, etc.).

[0041] In addition, the auxiliary voltage V1 serves as a source for a
first supply voltage V3 for the microcontroller CTR having a magnitude of
3.3 V, for example. The first supply voltage V3 for the controller CTR is
generated very accurately from the auxiliary voltage V1 with the aid of a
second voltage regulating circuit in the form of a series regulator LR.

[0042] The auxiliary voltage V1 provided by the buck controller TS
additionally serves as a source for a second supply voltage V2 for the
driver circuit having a magnitude of 15 V, for example. In this exemplary
embodiment, the second supply voltage V2 is generated from the auxiliary
voltage V1 by a third voltage regulating circuit in the form of a boost
controller HS.

[0043] As illustrated in FIG. 1, the boost controller HS contains an
inductance L, a diode D and a transistor Q. In order to generate a second
supply voltage V2 that is higher than the auxiliary voltage V1, the
transistor Q of the boost controller HS is driven with a high-frequency
rectangular signal. The greater the frequency of the rectangular signal,
the smaller the dimensions with which the inductance of the boost
controller HS can be embodied.

[0044] The rectangular signal for the transistor Q of the boost controller
HS (the control signal of the invention) is generated by the
microcontroller CTR. In this case, the controller CTR drives the boost
controller HS only if the driver circuit DR is intended to drive the
power semiconductor bridge LHB and if a fault-free program flow is
present in the CTR. This means that the generation of the rectangular
signal is only possible if the cyclic software-side program processing in
the CTR has no faults and all external conditions are met. A watchdog
function is thereby fulfilled at the same time. It is thereby possible to
prevent incorrect driving of the power semiconductor bridge LHB for
example in standby or during the initialization of the microcontroller.
In addition, a so-called watchdog function can be realized in this way
without additional circuits and components.

[0045] The regulation of the desired voltage magnitude of the second
supply voltage V2 for the driver circuit DR can be effected for example
"externally" by a comparator circuit. The latter compares the output
voltage via a corresponding voltage divider with a reference value and
locks the control signal of the microcontroller CTR in the case where the
predefined reference value is exceeded. If the reference value is then
undershot again with a hysteresis, the control signal of the
microcontroller CTR is again "allowed through" to the transistor Q of the
boost controller HS.

[0046] Alternatively, the regulation of the magnitude of the second supply
voltage V2 can also be performed by the microcontroller CTR itself. In
this case, by way of example, the generated voltage is fed back via a
corresponding voltage divider to the microcontroller CTR in order to
enable or block the control signal by an internal logic of the
microcontroller CTR.

[0047] If no control signal is supplied to the boost controller HS by the
controller CTR, the second supply voltage V2 for the driver circuit DR is
approximately at the potential of the auxiliary voltage V1 minus the
forward voltage of the diode D of the boost controller HS. This reduced
second supply voltage does not suffice, however, to drive the power
semiconductor bridge LHB since the driver circuit DR typically has an
undervoltage shutdown.

[0048] FIG. 2 shows a second exemplary embodiment of a circuit
construction for providing a supply voltage for the driver circuit DR
from FIG. 3. In this case, identical or analogous components are provided
with the same reference symbols as in FIG. 1.

[0049] In this exemplary embodiment, the third voltage regulating circuit
is realized by a charge pump LP. The charge pump LP has three
series-connected diodes, three capacitors C1, C2 and C3, an amplifier
gate and an inverting gate. The control signal from the microcontroller
CTR connects the capacitors C1 and C2 to the auxiliary voltage V1 or to
earth alternately and in an inverted fashion by means of the amplifier
and inverting gates. This results in charge transport to the third
capacitor C3 of the charge pump LP, at a voltage V2 three times higher
than the auxiliary voltage V1.

[0050] In this embodiment, too, the magnitude of the second supply voltage
V2 for the driver circuit DR, analogously to the first exemplary
embodiment, can optionally be regulated by the microcontroller CTR itself
or by an "external" circuit.

[0051] The remaining components and the modes of functioning thereof
correspond to those of the first exemplary embodiment above.

[0052] While in the two abovementioned exemplary embodiments in FIGS. 1
and 2, the second supply voltage V2 for the driver circuit DR is in each
case chosen to be greater than the auxiliary voltage V1 generated from
the intermediate circuit voltage V+ by the buck controller TS and is
accordingly increased from 5.5 V to 15 V, for example, by a boost
controller HS or a charge pump LP as the third voltage regulating
circuit, there is also the possibility, in principle, of choosing the
second supply voltage V2 for the driver circuit DR to be less than the
auxiliary voltage V1 generated from the intermediate circuit voltage V+
by the buck controller TS and accordingly of decreasing the second supply
voltage by a buck controller as the third voltage regulating circuit.